Rotation in Geant-4

Two main ways in the Geant-4 to apply the rotation: G4Rotation matrix and the HepRotation. Here the G4RotationMatrix.hh will be used.

Main reference

1. http://www.apc.univ-paris7.fr/~franco/g4doxy4.10/html/examples_2extended_2geometry_2transforms_2src_2_detector_construction_8cc_source.html
2. https://www-zeuthen.desy.de/geant4/g4course2011/day2/2_material/DetectorConstruction_8cc-source.html
3. http://nucleus.usask.ca/Geant/Exercises/rotations.html

In the Geometry.cc, the target is set by

SetPhysVol(name,solid,material,fPVolWorld,G4ThreeVector(0,ypos,zpos)) // line 915

add the rotation matrix as the paramter

#include "G4RotationMatrix.hh"

Geometry::SetPhysVol( const G4String& name, G4VSolid* solid,
		      G4Material* material, G4VPhysicalVolume* mtrVol,
		      const G4ThreeVector& transVec, G4RotationMatrix* rotm  )